A friction material is usually composed of sintered metal or fiber mat which normally is impregnated with a phenolic resin. The friction material is commonly cut from a continuous strip of rectangular sheeting composed of the friction material which is fed through the die or cutting apparatus. The friction material may be relatively expensive and, therefore, it is desirable to optimize the elimination of waste from the manufacturing process.
Further, elimination of waste product from the manufacture process assists in meeting compliance standards. The proper disposal of any scrap is the focus of increasing regulation by current environmental regulators. Any scrap resulting from the cutting process must be disposed of in an appropriate manner and, because of the materials from which the friction facing is manufactured, this disposal is becoming increasingly costly.
Further, in the interest of optimizing the useful life of the product to which the friction material is applied, operational smoothness, and cooling efficiency for the end use product, the literature and art relating to friction material provides numerous designs producing a large variety of friction facing materials and designs of friction facing materials. A common friction facing, currently available is shown by the disclosure of U.S. Pat. Nos. 4,260,047 and 4,674,616 which disclose friction discs, for use with clutches, which are formed from friction material and produced from the joining of a plurality of separate arcuate segments. The arcuate segments are pre-grooved to allow cooling oil to flow across the friction facing during clutch operation.
U.S. Pat. Nos. 5,094,331, 5,460,255, 5,571,372, 5,776,288, 5,897,737 and 6,019,205 disclose clutch friction plates having a large number of friction material segments on the plate. The segments are spaced such that an oil groove is provided between every adjacent segment.
U.S. Pat. Nos. 3,871,934 and 4,002,225 show a friction material wound around the outer periphery disc, such that it overlaps the disc on both sides. The overlap is then cut at intervals around the periphery and folded onto the surface of the disc.
U.S. Pat. No. 5,335,765, discloses a friction member having sets of first grooves and second grooves disposed in a radial plane and inclined obliquely backwardly in relation to the direction of rotation.
U.S. Pat. Nos. 5,615,758 and 5,998,311 show friction yarn facing materials with no grooves, but rather, the warp and fill yarns form channels to allow for the flow of fluid therethrough.
The manufacturing of each of these friction materials produces a large amount of unused or scrap material. It is, therefore, one object of the invention to effectively reduce the amount of scrap remaining after cutting of the friction material.
It is also desired that the sufficient cooling and lubrication of the friction material occur such that smooth engagement and disengagement of the end use product is maintained without creating excessive wear on the end use product and the friction material. Many prior art friction material designs incorporate the use of grooves or slot patterns within the facing material to achieve the desired cooling and lubrication by allowing the passage of a fluid such as oil through the friction facings. Such cooling grooves are generally produced from one of three labor-intensive methods. One method provides that the friction material is pre-grooved prior to being cut and applied to the clutch plate in a manner such as that shown by U.S. Pat. No. 4,260,047. Another method of producing grooves utilizes configured tooling to compress portions of the friction material during the bonding process. The third method involves producing cut grooves in a finished friction plate by mounting the plate onto a fixture and passing multiple milling and grinding wheels through the friction material to cut distinct grooves of desired depth and definition.
The common failing of the previous designs of friction materials lies in the formation of intricate shapes and designs which consequently leads to manufacturing complexities, increased scrap production and the resultant concerns regarding proper disposal of the scrap. Further, the previous friction materials are all individually manufactured to specific types of friction clutches and, generally speaking, cannot be used in a wide variety of applications.
It is an object of the present invention to manufacture a friction material having distinct cooling groove patterns of desired depth and definition without the need for secondary operations and attendant machinery.
It is yet another object of the present invention to provide a friction material having a plurality of desired grooves therein.
Yet another object of the invention is to provide friction material having structural advantages designated to produce enhanced production performance, and specifically durability, thermal stability, and compression set.
Yet a further object of the invention is to produce a friction material having the capability of maintaining static pressure and holding dynamic fluid flow within the grooves of the friction material during operation of the end use product.
It is another object of the invention to provide a friction material which is universally applicable to differing types of end use products. The friction material are especially useful with power transmission-energy absorption assemblies such as clutches, brakes, automatic transmissions, limited slip differentials, hoists, synchronizers, circular bands, discs, and the like end use products.